Increased intestinal permeability is associated with the development of multiple organ dysfunction syndrome in critically ill ICU patients

Insulin-like growth factor-1 levels contribute to the development of bacterial translocation in sepsis

RATIONALE

Many lines of evidence point toward the gastrointestinal (GI) tract in the pathophysiology of organ dysfunction in sepsis. Splanchnic hypoperfusion during sepsis leads to enterocyte apoptosis, diminished barrier function, and release of bacterial products. Sepsis lowers levels of insulin-like growth factor (IGF)-1, a known antiapoptotic factor. We recently demonstrated that treatment with IGF-1 is protective in murine sepsis.

OBJECTIVES

We hypothesize that decreased IGF-1 levels in sepsis contributes to the development of bacterial translocation.

METHODS

Sepsis was induced in C57BL/6 mice via intratracheal instillation of Pseudomonas aeruginosa. Human subjects with sepsis were enrolled if they had a documented positive blood culture with a nonenteric organism. Bacterial translocation was measured in serum by quantitative real-time polymerase chain reaction with primers specific for enteric bacteria. Serum IGF-1 was measured by ELISA. Apoptosis of the GI epithelium was assessed via immunohistochemistry.

MEASUREMENTS AND MAIN RESULTS

We found that mice with severe sepsis had evidence of bacterial translocation by 24 hours. Enteric bacterial load correlated inversely with levels of serum IGF-1. If we treated mice with IGF-1, bacterial translocation was significantly decreased. In addition, we found increased GI epithelial cell apoptosis after sepsis, which was significantly decreased after IGF-1 treatment. Human subjects with nonenteric sepsis developed progressive enteric bacteremia over 3 days. The degree of enteric bacteremia correlated inversely with serum IGF-1 levels.

CONCLUSIONS

These data support the hypothesis that sepsis-induced reductions in IGF-1 levels contribute to the development of bacterial translocation in both a murine model and human subjects.

Erythropoietin protects severe haemorrhagic shock-induced organ damage in conscious rats

OBJECTIVE

Erythropoietin (EPO) has pleiotropic cytoprotective actions. We investigated the effects of EPO on the physiopathology and cytokine levels after haemorrhagic shock (HS) in conscious rats.

METHODS

Rats received an intravenous injection of 300 U/kg EPO over 10 min followed by HS via withdrawal of 60% of total blood volume from a femoral arterial catheter (6 ml/100 g body weight) over 30 min. Mean arterial pressure (MAP) and heart rate (HR) were monitored continuously for 18 h after the start of blood withdrawal. Levels of biochemical parameters, including haemoglobin, GOT, GPT, BUN, creatinine (Cr), LDH, CPK, and lactate were measured at 30 min before the induction of HS and 0, 1, 3, 6, 9, 12, and 18 h after HS. Cytokine levels, including TNF-alpha and IL-6, in serum were measured at 1, 9, and 18 h after HS. The kidneys, liver, lungs, and small intestine were removed for pathology assessment at 48 h after HS.

RESULTS

HS significantly increased HR, blood GOT, GPT, BUN, Cr, LDH, CPK, lactate, TNF-alpha, and IL-6 levels and decreased haemoglobin and MAP in rats. Pre-treatment with EPO improved survival rate, preserved the MAP, decreased the tachycardia and markers of organ injury, suppressed the release of TNF-alpha and IL-6 after HS in rats.

CONCLUSION

Pre-treatment with EPO suppresses the release of serum TNF-alpha and IL-6, along with decreasing the levels of markers of organ injury associated with HS, with such actions ameliorating HS-induced organ damage in rats.

Endotoxin level in ischemia-reperfusion injury in rats: effect of glutamine pretreatment on endotoxin levels and gut morphology

OBJECTIVE

We aimed to investigate the effect of enteral glutamine (Gln) pretreatment on plasma endotoxin level and intestinal histopathologic changes during intestinal ischemia-reperfusion (I/R) injury in rats.

METHODS

Intestinal I/R was induced by 60-min occlusion of the superior mesenteric artery followed by 60 min of reperfusion. Animals were pretreated with Gln by orogastric route for different periods and doses. To investigate the effects of gut decontamination on intestinal I/R injury, animals were pretreated with neomycin sulfate and erythromycin phosphate by orogastric route. In another series, dl-alpha-tocopherol hydrogen succinate was used to investigate the effects of vitamin E on intestinal I/R injury. Plasma endotoxin level was measured by the colorimetric "limulus amebocyte lysate" test. Intestinal mucosal injury was scored on a scale described by Chiu et al. (Archive in Surgery 1970;101:478-483).

RESULTS

Intestinal I/R increased the plasma endotoxin level and worsened the histopathologic score significantly. Gln pretreatment (1g/kg) for 4 d reduced the I/R-induced elevation of plasma endotoxin level. However, a significant improvement in histopathologic score could only be achieved when the pretreatment was given for 7 d. Antibiotic pretreatment lowered plasma endotoxin level without affecting the I/R-induced histopathologic changes, whereas vitamin E pretreatment affected plasma endotoxin level and histopathologic changes.

CONCLUSION

These results suggest a lack of association between plasma endotoxin level and intestinal histopathologic alterations in intestinal I/R.

Early weaning stress impairs development of mucosal barrier function in the porcine intestine

Early life stress is a predisposing factor for the development of chronic intestinal disorders in adult life. Here, we show that stress associated with early weaning in pigs leads to impaired mucosal barrier function. Early weaning (15- to 21-day weaning age) resulted in sustained impairment in intestinal barrier function, as indicated by reductions in jejunal transepithelial electrical resistance and elevations in mucosal-to-serosal flux of paracellular probes [(3)H]mannitol and [(14)C]inulin measured at 5 and 9 wk of age, compared with that shown in late-weaned pigs (23- to 28-day weaning age). Elevated baseline short-circuit current was observed in jejunum from early-weaned pigs and was shown to be mediated via enhanced Cl(-) secretion. Jejunal barrier dysfunction in early-weaned pigs coincided with increased lamina propria immune cell density particularly mucosal mast cells. The mast cell stabilizer drug sodium cromoglycolate ameliorated barrier dysfunction and hypersecretion in early-weaned pigs, demonstrating an important role of mast cells. Furthermore, activation of mast cells ex vivo with c48/80 and corticotrophin-releasing factor (CRF) in pig jejunum mounted in Ussing chambers induced barrier dysfunction and elevations in short-circuit current that were inhibited with mast cell protease inhibitors. Experiments in which selective CRF receptor antagonists were administered to early-weaned pigs revealed that CRF receptor 1 (CRFr1) activation mediates barrier dysfunction and hypersecretion, whereas CRFr2 activation may be responsible for novel protective properties in the porcine intestine in response to early life stress.

Endoscopic clips prevent displacement of intestinal feeding tubes: a long-term follow-up study

BACKGROUND

Displacement of jejunal feeding tubes is a major problem in enteral feeding. Although endoscopic clips have been used to prevent migration of the tube during placement, the long-term effect of the clips on tube displacement is unknown.

OBJECTIVES

The purpose of this study was to examine the long-term effect of endoscopic clips on preventing displacement of the jejunal feeding tube.

DESIGN

A retrospective study.

SETTING

A single tertiary medical center.

MAIN OUTCOME MEASUREMENTS

The success rate of the procedure and the functional duration of the feeding tube.

RESULTS

About 93% of patients had a percutaneous endoscopic gastrostomy jejunal (PEGJ) tube successfully placed with use of endoscopic clips. About 7% had tube migration and repeat procedures were successful. The mean functional duration of the tube was 55 days. Limitations Retrospective, single-center.

CONCLUSIONS

Use of endoscopic clips can prevent migration during placement of the feeding tube and can also reduce tube displacement in the long term.

A model of the isolated perfused rat small intestine

Intestinal edema remains a serious clinical problem, and novel approaches to study its pathophysiology are needed. It was our aim to develop a long-term stable isolated perfused rat small bowel preparation permitting analysis of vascular, luminal, interstitial, and lymphatic compartments and to demonstrate the utility of this model by studying the effects of the proinflammatory mediator platelet-activating factor (PAF). A temperature-controlled chamber with an integrated balance was designed to perfuse isolated intestines through the mesenteric artery and the gut lumen. Steroids or oxygen carriers were not needed. Functional and morphological integrity of the tissue was preserved for several hours as confirmed by oxygen consumption, venous lactate-to-pyruvate ratio, arterial and venous pH, lactose digestion and galactose uptake, intravascular and luminal pressures, maintained fluid homeostasis, gut motility, and quantitative light microscopic analysis. Administration of PAF caused typical effects such as vasoconstriction, gut atony, and loss of galactose uptake. PAF also elicited a transient loss of 20% of the perfusate liquid from the mesenteric vascular bed, two-thirds of which were transferred to the lumen. All these responses were entirely reversible. This new model provides detailed insights into the physiology of the small intestine and will allow to study fundamental processes such as fluid homeostasis, barrier functions, transport mechanisms, and immune responses in this organ. Using this model, here we show a dramatic and yet reversible response of the rat small bowel to PAF, suggesting luminal water clearance as a novel safety factor in the intestine that may be of clinical relevance.

Diagnosing malabsorption in the intensive care unit

Malabsorption as a result of decreased intestinal function is a frequently occurring problem in intensive care units. Small bowel dysfunction may lead to malnutrition and may predispose patients to infectious complications (sepsis) and may be linked to increased hospitalization duration, morbidity and mortality. There are several small bowel function tests, such as faecal fat excretion and sugar absorption tests, but data specifically applicable to the intensive care setting are limited. Moreover, there are multiple confounders such as altered intestinal permeability, changed transit time and renal dysfunction. A more specific test, fasting plasma citrulline concentration, has poor test characteristics for detection of decreased intestinal function in patients with dysfunctional enterocytes. Therefore, a citrulline generation test was recently developed in order to measure the conversion of glutamine (administered either enterally or intravenously) into citrulline. This conversion takes place exclusively in a properly functioning enterocyte; therefore, citrulline generation upon glutamine stimulation may be a promising biomarker for assessment of the small bowel function.

Melatonin ameliorates hemorrhagic shock-induced organ damage in rats

BACKGROUND

Hemorrhagic shock (HS) followed by resuscitation can result in production of several inflammatory mediators, such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), leading to multiple organ dysfunction. Melatonin can attenuate organ damage with its anti-inflammation effects. The present study was designed to investigate the effects of melatonin on the physiopathology and cytokine levels after HS in rats.

METHODS

HS was induced in rats by withdrawing 40% of the total blood volume (6 mL/100 gm body weight) from a femoral artery catheter, immediately followed by intravenous injection of 10mg/kg melatonin. Mean arterial pressure and heart rate were monitored continuously for 48 h after the start of blood withdrawal. Biochemical parameters, including levels of hemoglobulin, glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), blood urea nitrogen (BUN), creatinine (Cre), lactic dehydrogenase (LDH), creatine phosphokinase (CPK), and lactate, were determined 30 min before and 0, 1, 3, 6, 12, 24, and 48 h after induction of HS while an equal volume of normal saline was replaced as fluid resuscitation. Cytokine levels including TNF-α and IL-6 in the serum were measured at 1, 24, and 48 h after HS. The kidney, liver, lung, and small intestine were removed for pathology assessment at 48 h after HS.

RESULTS

HS significantly increased the heart rate, blood GOT, GPT, BUN, Cre, LDH, CPK, lactate, TNF-α, and IL-6 levels, and decreased hemoglobulin and mean arterial pressure in rats. Treatment with melatonin preserved the mean arterial pressure, decreased tachycardia, and markers of organ injury, and suppressed the release of TNF-α and IL-6, with no change in hemoglobulin after HS in rats.

CONCLUSION

Treatment with melatonin suppresses the release of serum TNF-α and IL-6, and decreases the levels of markers of organ injury associated with HS, thus ameliorating HS-induced organ damage in rats.

Orexigenic hormone ghrelin ameliorates gut barrier dysfunction in sepsis in rats

OBJECTIVES

We have recently shown that ghrelin, a novel orexigenic hormone, is reduced in sepsis. Ghrelin treatment, mediated through ghrelin receptors in the brain, attenuates sepsis-induced inflammation and mortality. Gut barrier dysfunction is common in sepsis. High-mobility group B1 (HMGB1) increases gut permeability both in vitro and in vivo. However, it remains unknown whether ghrelin has any effects on HMGB1 and gut barrier function in sepsis. We hypothesized that ghrelin decreases HMGB1 release and attenuates sepsis-induced gut barrier dysfunction through central ghrelin receptors.

DESIGN

Prospective, controlled, and randomized animal study.

SETTING

A research institute laboratory.

SUBJECTS

Male adult Sprague-Dawley rats (275-325 g).

INTERVENTIONS

Cecal ligation and puncture (CLP) followed by injection/infusion of ghrelin.

MEASUREMENTS AND MAIN RESULTS

Five hours after CLP, a bolus intravenous injection of 2 nmol of ghrelin was followed by a continuous infusion of 12 nmol of ghrelin via an osmotic mini-pump for 15 hrs. Twenty hours after CLP, brain ghrelin levels, serum HMGB1 levels, ileal mucosal permeability to fluorescein isothiocyanate dextran, bacterial counts in the mesenteric lymph nodes complex, and gut water content were determined. In additional groups of animals, bilateral trunk vagotomy was performed at 5 hrs after CLP before ghrelin injection. Furthermore, to confirm the role of central ghrelin receptors in ghrelin's effect, ghrelin (1 nmol) was administered through intracerebroventricular injection at 5 hrs after CLP. Our results showed that brain levels of ghrelin decreased by 34% at 20 hrs after CLP. Intravenous administration of ghrelin completely restored brain levels of ghrelin, significantly reduced the elevated HMGB1 levels, and attenuated gut barrier dysfunction. Vagotomy eliminated ghrelin's inhibition of HMGB1 and attenuation of gut barrier dysfunction. Intracerebroventricular injection of ghrelin decreased serum HMGB1 levels and ameliorated gut barrier dysfunction.

CONCLUSIONS

Ghrelin reduces serum HMGB1 levels and ameliorates gut barrier dysfunction in sepsis by vagus nerve activation via central ghrelin receptors. Ghrelin can be further developed as a novel agent to protect gut barrier function in sepsis.

The physiologic response and associated clinical benefits from provision of early enteral nutrition

Provision of enteral nutrition (EN) to critically ill patients early upon admission to the intensive care unit exerts a beneficial physiologic effect that downregulates systemic immune responses, reduces oxidative stress, and improves patient outcome. Adding specific pharmaconutrient agents to EN in certain patient populations has a synergistic effect, magnifying the degree of this favorable physiologic response. In contrast, failure to provide enteral nutrients creates a physiologic profile that exacerbates oxidative stress and increases the systemic inflammatory response syndrome. Unfortunately, parenteral nutrition (PN) in the form and manner currently provided in North America does not appear to mimic the same physiologic response seen with EN. In the future, use of alternative fuel sources, steps to promote better tolerance of EN, and innovative strategies for delivery of both EN and PN may serve to further enhance the physiologic effect of nutrition therapy and to achieve even greater improvement in patient outcome.

Fasting-induced intestinal damage is mediated by oxidative and inflammatory responses

Background

Green tea has been shown to repair fasting-induced mucosal damage in rat intestine. The aim of this study was to elucidate the underlying mechanism.

Methods

Five groups of rats were used. Group 1 had free access to chow diet and water, and those in group 2 were fasted for 3 days. Animals in group 3 were fasted for 3 days, then were allowed drinking water for a further 7 days. Groups 4 and 5 were fasted for 3 days, then given drinking water containing green tea or vitamin E respectively for 7 days. Blood was collected for estimation of total plasma antioxidants, and jejunal samples were used for immunohistochemical analysis of superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx), and for estimation of myeloperoxidase (MPO) activity.

Results

Use of green tea was associated with a significant increase in total plasma antioxidants (P < 0·001), and mucosal SOD (P < 0·001), catalase (P = 0·006) and GPx (P = 0·017), but a significant decrease in MPO activity (P < 0·001). Vitamin E produced similar changes, but the effects were smaller.

Conclusion

Green tea reverses the fasting-induced damage to the intestinal mucosa by its antioxidant and anti-inflammatory effect.

Acute stress increases colonic paracellular permeability in mice through a mast cell-independent mechanism: involvement of pancreatic trypsin

AIMS

Increased colonic paracellular permeability (CPP) is a key feature of gastro-intestinal disorders as irritable bowel syndrome and inflammatory bowel diseases. Stress stimulates exocrine pancreatic secretion through cholinergic pathways, and trypsin is known to increase CPP. Consequently we have investigated in this work whether trypsin released into the gut lumen following an acute stress may participate to the short-term increase in CPP.

MAIN METHODS

Mice were treated with atropine or a non-selective CRF (corticotropin-releasing factor) receptor antagonist (alpha-helical CRF (9-41)), before being submitted to a 2-h stress session. Then, CPP and protease activity in colonic contents (total proteolytic, trypsin activity, and mouse mast cell protease (MMCP)-1 levels) were determined. The effects of colonic contents from sham-stressed or stressed animals on CPP were evaluated in mice colonic tissues mounted in Ussing chambers, in presence or not of soybean trypsin inhibitor (SBTI) or FSLLRY, a protease-activated receptor-2 (PAR2) antagonist.

KEY FINDINGS

Acute stress significantly increased CPP, proteolytic and trypsin activities, and MMCP-1 levels. Atropine inhibited stress-induced impairment of CPP and strongly diminished total proteolytic and trypsin activities in stressed animals, but not MMCP-1 levels. Colonic contents from stressed animals increased CPP in mice tissues, this effect being inhibited by SBTI and PAR2 antagonist.

SIGNIFICANCE

Acute stress activates cholinergic pathways, to trigger exocrine pancreatic secretion. Trypsin, released in these conditions, may be responsible for colonic barrier alterations through the activation of PAR2.

Erythropoietin inhibits the increase of intestinal labile zinc and the expression of inflammatory mediators after traumatic brain injury in rats

BACKGROUND

The objective of this study was to determine the effect of erythropoietin (Epo) on the intestinal labile zinc and the inflammatory factor in rats after traumatic brain injury (TBI).

METHODS

Male Sprague-Dawley rats were randomly divided into nine groups: (a) normal group; (b) sham-operation group; (c, d, e, f, and g) TBI group, killed at 1 hour, 6 hour, 24 hour, and 72 hour and 7 days postinjury, respectively; (h and i) TBI + saline and TBI + Epo, killed at 24 hour or 72 hour postinjury. Parietal brain contusion was produced by a free-falling weight on the exposed dura of the right parietal lobe. Intestinal labile zinc, the tumor necrosis factor-alpha, interleukin (IL)-8, and wet/dry weight ratio were investigated in different groups.

RESULTS

The gut contains a certain amount of labile zinc in normal animals and TBI caused obviously gradual increment of intestinal liabled zinc. The levels of inflammatory mediators and the gut wet/dry weight ratio were also found to increase in the trauma group (p < 0.05). There was a highly positive correlation between the abundance of zinc fluorescence and these proinflammation factors. Epo significantly reduced the intestinal labile zinc, the inflammatory mediators, and the gut wet/dry weight ratio compared with TBI group (p < 0.05).

CONCLUSIONS

Epo can protect intestine from TBI-induced injury by attenuating intestinal inflammation and labile zinc accumulation in vivo.

Fluvastatin attenuates severe hemorrhagic shock-induced organ damage in rats

OBJECTIVES

Multiple organ dysfunction resulting from hemorrhagic shock (HS) and subsequent resuscitation was mediated by several inflammatory factors such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10). The present study was designed to investigate the protective effects of fluvastatin on these mediators after HS in rats.

METHODS

The experimental rats were randomly divided into three groups. The vehicle group received only vitamin K without HS, the HS-control group received vitamin K and HS, and the HS-experimental group received both vitamin K and fluvastatin (1mg/kg) before HS. HS was produced by bleeding from a femoral arterial catheter to remove 60% of total blood volume (6ml/100g BW) over 30min. The mean arterial pressure (MAP) and heart rate (HR) were monitored continuously for 12h after the start of blood withdrawal. The biochemical parameters, including arterial blood gas, glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT), blood urea nitrogen (BUN), creatinine (Cre), lactic dehydrogenase (LDH), creatine phosphokinase (CPK), and lactate were obtained at 30min before induction of HS and at 0, 1, 3, 6, 9 and 12h after HS. Equal volume of normal saline was given to replace blood volume loss. Cytokine levels including TNF-alpha and IL-10 in serum were measured at 1h after HS. Kidney, liver, lung and small intestine were removed for pathology examination at 48h after HS.

RESULTS

HS significantly increased HR, blood GOT, GPT, BUN, Cre, LDH, CPK, lactate, TNF-alpha and IL-10 levels, and also induced metabolic acidosis and decreased MAP in rats. Pre-treatment with fluvastatin was found to improve survival rate, preserved MAP, decreased the markers of organ injury, suppressed the release of TNF-alpha and increased IL-10 after HS in rats.

CONCLUSION

Pre-treatment with fluvastatin can suppress the release of serum TNF-alpha and can also increase serum IL-10 level to protect HS-induced multi-organ damage in rats.

Future possibilities for the treatment of septic shock with herbal components

The treatment of septic shock remains challenging even with the armamentarium of modern antibiotics and intensive care technologies. Reliance on antibiotics and other methods targeting modulation of the systemic inflammatory response such as steroids, hemofiltration, and cytokine antagonists has not led to reliable successful treatment for inflammation and infection-related shock. In part, this is attributable to the continuous evolution of antibacterial drug resistance. Herbal medicine has been used in treating infections and shock, worldwide, for thousands of years. The active components contained in these naturally occurring products usually have one or more of the following properties: (1) direct attack or suppression on bacterial pathogens, (2) modulation of the host's immune system resulting in suppression of inflammation and overproduction of inflammatory mediators, and (3) neutralization of toxic free-radicals. In vitro and in vivo animal and human clinical studies of herbal medicines' effectiveness in the treatment of septic shock are needed. Their pharmacological mechanisms need to be elucidated at molecular level to investigate and improve targeted therapy using heretofore unexplored uses for traditional herbal remedies. Herein, we discuss historical examples of herbal remedies used to fight infection. In addition, we discuss the use of herbal and traditional medicines as potential adjuncts in the ongoing battle against septic shock and systemic infections.

Comparison of the chloride channel activator lubiprostone and the oral laxative Polyethylene Glycol 3350 on mucosal barrier repair in ischemic-injured porcine intestine

AIM: To investigate the effects of lubiprostone and Polyethylene Glycol 3350 (PEG) on mucosal barrier repair in ischemic-injured porcine intestine.

METHODS: Ileum from 6 piglets (approximately 15 kg body weight) was subjected to ischemic conditions by occluding the local mesenteric circulation for 45 min in vivo. Ileal tissues from each pig were then harvested and mounted in Ussing chambers and bathed in oxygenated Ringer’s solution in vitro. Intestinal barrier function was assessed by measuring transepithelial electrical resistance (TER) and mucosal-to-serosal fluxes of ³H-mannitol and ¹⁴C-inulin. Statistical analyses of data collected over a 120-min time course included 2-way ANOVA for the effects of time and treatment on indices of barrier function.

RESULTS: Application of 1 μmol/L lubiprostone to the mucosal surface of ischemic-injured ileum in vitro induced significant elevations in TER compared to non-treated tissue. Lubiprostone also reduced mucosal-to-serosal fluxes of ³H-mannitol and ¹⁴C-inulin. Alternatively, application of a polyethylene laxative (PEG, 20 mmol/L) to the mucosal surface of ischemic tissues significantly increased flux of ³H-mannitol and ¹⁴C-inulin.

CONCLUSION: This experiment demonstrates that lubiprostone stimulates recovery of barrier function in ischemic intestinal tissues whereas the PEG laxative had deleterious effects on mucosal repair. These results suggest that, unlike osmotic laxatives, lubiprostone stimulates repair of the injured intestinal barrier.

Transcription factor Nrf2 plays a pivotal role in protection against traumatic brain injury-induced acute intestinal mucosal injury in mice

BACKGROUND

Traumatic brain injury (TBI) can induce an acute intestinal mucosal injury. Nuclear factor erythroid 2-related factor 2 (Nrf2) has a unique role in many physiological stress processes, but its contribution to intestinal mucosal injury after TBI remains to be determined.

MATERIALS AND METHODS

Wildtype Nrf2 (+/+) and Nrf2 (-/-) deficient mice were subjected to a moderately severe weight-drop impact head injury. Intestinal mucosal morphological changes, plasma endotoxin, intestinal permeability, apoptosis, inflammatory cytokines, and antioxidant/detoxifying enzymes were measured at 24 hours after TBI.

RESULTS

Nrf2 deficient mice were found to be more susceptible to TBI-induced acute intestinal mucosal injury, as characterized by the higher increase in gut structure damage, plasma endotoxin, intestinal permeability, and apoptosis after TBI. This exacerbation of intestinal mucosal injury in Nrf2 deficient mice was associated with increased intestinal mRNA and protein expression of inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-1beta and interleukin-6, and with decreased intestinal mRNA expression and activity levels of antioxidant and detoxifying enzymes including NAD(P)H: quinone oxidoreductase 1 (NQO1) and glutathione S-transferase alpha-1 (GST-alpha1), compared with their wildtype Nrf2 (+/+) counterparts after TBI.

CONCLUSIONS

We show for the first time that mice lacking Nrf2 are more susceptible to TBI-induced acute intestinal mucosal injury. Our data suggests that Nrf2 plays an important role in protecting TBI-induced intestinal mucosal injury, possibly by regulating of inflammatory cytokines and inducing of antioxidant and detoxifying enzymes.

The emerging role of the gut in chronic heart failure

PURPOSE OF REVIEW

Chronic heart failure is a multisystem disease with increased sympathetic tone, an anabolic/catabolic dysbalance, and chronic inflammation. Recent studies suggest an altered morphology, permeability, and absorption of the digestive tract in chronic heart failure. Due to nonocclusive mesenterial ischaemia and disturbed intestinal microcirculation, bacterial endotoxin is thought to enter the bloodstream through the hypoperfused, oedematous gut wall, thereby triggering an inflammatory response. Circulating cytokines act as cardiosuppressors. Their plasma levels predict increased mortality in chronic heart failure.

RECENT FINDINGS

The present article focuses on specific alterations of the gastric, small intestinal, and large intestinal region in chronic heart failure. It describes the leaky intestinal barrier with an augmented bacterial biofilm that may contribute to chronic inflammation and malnutrition. Furthermore, we review methods for bowel perfusion measurement and potential therapeutic approaches.

SUMMARY

It remains unclear whether increased adherent bacteria in patients with chronic heart failure are a primary or secondary event and whether they contribute to systemic inflammation. Both lack of mucosal integrity with consecutive local and systemic inflammation and dysfunction of transport proteins may worsen the clinical symptoms of chronic heart failure. Therefore, future studies need to address the pathophysiology of the intestinal barrier whose reactivity seems to be crucial for heart function.

The cytokine storm and factors determining the sequence and severity of organ dysfunction in multiple organ dysfunction syndrome

Multiple organ dysfunction syndrome (MODS) is a major cause of morbidity and mortality in intensive care units. It is being encountered frequently in critically ill patients owing to advancements in organ-specific supportive technologies to survive the acute phase of severe sepsis and shock. It is now believed that MODS is the result of an inappropriate generalized inflammatory response of the host to a variety of acute insults. The pathologic mechanisms of MODS were reviewed, and factors determining the sequence and severity of organ dysfunction were discussed in depth. In the early phase of MODS, circulating cytokines cause universal endothelium injury in organs. In the later phase of MODS, overexpression of inflammatory mediators in the interstitial space of various organs is considered a main mechanism of parenchyma injury. The difference in constitutive expression and the upregulation of adhesion molecules in vascular beds and the density and potency of intrinsic inflammatory cells in different organs are the key factors determining the sequence and severity of organ dysfunction. By activating the intrinsic inflammatory cell in a distant organ, organ dysfunctions are linked in a positive feedback loop through circulating inflammatory mediators. Antagonists targeted at adhesion molecules may alleviate the severity of endothelial damage. And nonsteroidial anti-inflammatory drugs or steroids administered judiciously in the early phase of MODS may retard the progress of multiple organ failure.

Gut luminal lactate measured by microdialysis mirrors permeability of the intestinal mucosa after ischemia

The aim of the present study was to investigate the influence of a prolonged initial intestinal ischemic insult on transmucosal permeability after a subsequent ischemic event and whether microdialysis of biomarkers released to the gut lumen is able to reflect changes in intestinal permeability. The superior mesenteric artery was cross-clamped for 60 min followed by 4 h of reperfusion in 16 pigs. Nine pigs had a second cross-clamp of 60 min and 3 h of reperfusion, whereas seven pigs were observed for a further 4 h of reperfusion. Intestinal mucosal integrity was assessed by permeability of C-polyethylene glycol (PEG-4000) over the gut mucosa, luminal microdialysis of lactate, glucose and glycerol, and tonometry. During reperfusion, the PEG-4000 amount in venous blood was two times higher after the first than after the second ischemia (area under the curve, 44,780 [13,441-82,723] vs. 22,298 (12,213-49,698] counts min mL(-1), P=0.026 [mean {range}]). There was less lactate detected in the gut lumen after the second ischemia compared with the first (area under the curve, 797 [412-1,700] vs. 1,151 [880-1,969] mmol min L(-1), P=0.02) and a lower maximum concentration (4.8 [2.7-9.4] vs. 8.5 [5.0-14.9] mM, P=0.01). The same pattern was also seen for luminal glycerol and glucose. During the second ischemia, the intestinal mucosal/arterial CO2 gap was identical to the level during the first ischemic episode. A prolonged ischemic insult of the intestine confers protection, for reduced hyperpermeability against further ischemia. Microdialysis of biomarkers mirrors permeability changes associated with this type of protection. Lactate reflects permeability across the intestinal mucosa more precisely than glycerol.

Enteral glutamine pretreatment does not decrease plasma endotoxin level induced by ischemia-reperfusion injury in rats

AIM: To investigate whether oral glutamine pretreatment prevents impairment of intestinal mucosal integrity during ischemia-reperfusion (I/R) in rats.

METHODS: The study was performed as two series with 40 rats in each. Each series of animals was divided into four groups. The first group was used as a control. Animals in the second group were only pretreated with oral glutamine, 1 g/kg for 4 d. The third group received a normal diet, and underwent intestinal I/R, while the fourth group was pretreated with oral glutamine in the same way, and underwent intestinal I/R. Intestinal mucosal permeability to ⁵¹Cr-labeled EDTA was measured in urine in the first series of animals. In the second series, histopathological changes in intestinal tissue and plasma endotoxin levels were evaluated.

RESULTS: Intestinal I/R produced a significant increase in intestinal permeability, plasma endotoxin level and worsened histopathological alterations. After intestinal I/R, permeability was significantly lower in glutamine-treated rats compared to those which received a normal diet. However, no significant change was observed in plasma endotoxin levels or histopathological findings.

CONCLUSION: Although glutamine pretreatment seems to be protective of intestinal integrity, upon I/R injury, such an effect was not observable in the histopathological changes or plasma endotoxin level.

Gut hyperpermiability after ischemia and reperfusion: attenuation with adrenomedullin and its binding protein treatment

Ischemia bowel remains a critical problem resulting in up to 80% mortality. The loss of gut barrier function plays an important role. Our previous studies have shown that administration of adrenomedullin (AM), a novel vasoactive peptide, and its binding protein (AMBP-1), reduces the systemic inflammatory response and organ injury after systemic ischemia induced by hemorrhagic shock. However, it remains unknown whether administration of AM/AMBP-1 preserves gut barrier function after gut ischemia reperfusion (I/R). We therefore hypothesized that AM/AMBP-1 prevents structural and functional damages to the intestinal mucosa after gut I/R. To test this, gut ischemia was induced by placing a microvascular clip across the superior mesenteric artery (SMA) for 90 min in male adult rats. After release of the SMA clamp, AM (12 mug/kg BW) and AMBP-1 (40 mug/kg BW) in combination or vehicle (1-ml normal saline) were administered intravenously over a period of 30 min. The mucosal barrier function in the small intestine was assessed in an isolated everted ileum sac using fluorescein-isothiocyanate dextran (FD4) at 4 h after AM/AMBP-1 treatment. FD4 clearance was used as a measure of gut permeability. In additional groups of animals, blood and small intestine samples were collected at 4 h after the treatment. Morphological changes in the small intestine were assessed by H-E staining. Serum concentrations of alanine aminotransferase, aspartate aminotransferase, total bilirubin, direct bilirubin, lactate and lactate dehydrogenase were also assessed. The gene expression and protein levels of TNF-alpha in the small intestine were determined by RT-PCR and ELISA, respectively. Our results showed that administration of AM/AMBP-1 significantly attenuated the development of intestinal mucosal hyperpermeability during the reperfusion. Treatment with AM/AMBP-1 dramatically improved I/R-induced intestinal mucosal damages, attenuated remote organ injury, and downregulated gene expression and protein levels of TNF-alpha in the small intestine. In conclusion, AM/AMBP-1 attenuates structural and functional damages to the intestinal mucosa, and it appears to be a novel treatment for reperfusion injury after gut ischemia. The beneficial effect of AM/AMBP-1 on gut barrier function after I/R is associated with downregulation of TNF-alpha.

RESISTANCE OF THE FEMALE, AS OPPOSED TO THE MALE, INTESTINE TO I/R-MEDIATED INJURY IS ASSOCIATED WITH INCREASED RESISTANCE TO GUT-INDUCED DISTANT ORGAN INJURY

We tested the hypothesis that the female intestine is more resistant to gut I/R injury than the male intestine by comparing the effects of the isolated pure gut I/R superior mesenteric artery occlusion (SMAO) model on gut morphology and whether SMAO-induced distant organ injury (lung, bone marrow [BM], neutrophils, and red blood cells [RBCs]) would differ between male and proestrus female rats. At 6 or 24 h after SMAO or sham SMAO, gut injury, lung permeability, pulmonary neutrophil sequestration, RBC deformability, and BM RBC and white blood cell progenitor growth were measured, as was the ability of the plasma from these rats to activate naive rat neutrophils. At both 6 and 24 h after SMAO, the female rats had significantly less intestinal injury and reduced gut-induced lung injury, BM suppression, RBC dysfunction, and neutrophil activation than male rats subjected to SMAO. These results indicate that the resistance of proestrus female rats to gut injury and gut-induced distant organ injury is greater than that observed in male rats.

Intravenous injection of trauma-hemorrhagic shock mesenteric lymph causes lung injury that is dependent upon activation of the inducible nitric oxide synthase pathway

OBJECTIVE

To test the hypothesis that gut-derived factors carried in trauma-hemorrhagic shock (T/HS) lymph is sufficient to induce lung injury. Additionally, because our previous studies showed that T/HS-induced nitric oxide production was associated with lung injury, we examined whether T/HS lymph-induced lung injury occurs via an inducible nitric oxide synthase (iNOS)-dependent pathway.

BACKGROUND

We have previously shown that T/HS-induced lung injury is mediated by gut-derived humoral factors carried in the mesenteric lymph. However, it remains unclear whether T/HS lymph itself is sufficient to induce lung injury, or requires the activation of other factors during the T/HS period to exert its effect.

METHODS

Mesenteric lymph collected from T/HS or trauma-sham shock (T/SS) animals was injected intravenously into male rats at a rate of 1 mL/h for 3 hours. At the end of infusion, lung injury was assessed by lung permeability and lung histology. The effect of iNOS inhibition on T/HS lymph-induced lung injury was studied and this was further confirmed in iNOS knockout mice. Finally, iNOS immunohistochemistry was performed to identify the cells of origin of iNOS.

RESULTS

The injection of T/HS lymph, but not sham shock lymph, caused lung injury. This was associated with increased plasma nitrite/nitrate levels as well as induction of iNOS protein in the lung, liver, and gut. Treatment with the selective iNOS inhibitor aminoguanidine prevented T/HS lymph-induced lung injury. iNOS knockout mice, but not their wild-type controls, were resistant to T/HS lymph-induced lung injury. By immunohistochemistry, neutrophils and macrophages, rather than parenchymal cells, were the source of T/HS lymph-induced lung iNOS.

CONCLUSIONS

These results indicate that T/HS lymph is sufficient to induce acute lung injury and that lymph-induced lung injury occurs via an iNOS-dependent pathway.

Splanchnic ischemia and gut permeability after acute brain injury secondary to intracranial hemorrhage

INTRODUCTION

Splanchnic ischemia (SI) and increased gut permeability (GP) have been described in acute brain injury (ABI), although their incidence and relation to the type and severity of injury are uncertain. The aim of this study was to evaluate the incidence of both abnormalities in a series of patients with severe ABI secondary to intracranial hemorrhage (ICH) managed with a resuscitation protocol pursuing adequate cerebral and systemic hemodynamics.

METHODS

Eight patients with severe ABI secondary to ICH were admitted to the ICU and were mechanically ventilated and monitored with intracranial pressure measurement, jugular bulb venous oxygen saturation, arterial lactate concentration and gastric tonometry. All patients were managed actively to maintain adequate blood and cerebral perfusion pressures with a protocol based on aggressive fluid resuscitation prior to vasoactive drugs administration. GP was assessed using the lactulose/mannitol test (LMT). Values were recorded during the first 7 days of hospital stay.

RESULTS

Arterial lactate concentration was within the normal range (1.9 +/- 0.5 mmol/l) in all patients. Upon admission, the mean pCO(2) gap was 8.2 +/- 4.3 mmHg (1.09 +/- 0.57 kPa) with an intramucosal pH of 7.4 +/- 0.1. All patients had an abnormal LMT (0.066 +/- 0.055) compared with 19 healthy volunteers (0.025 +/- 0.004) (p < 0.05, Mann Whitney test).

CONCLUSION

Splanchnic ischemia is uncommon among patients with acute brain injury secondary to intracranial hemorrhage, provided they are adequately resuscitated with a protocol based mainly on fluids to achieve an adequate CPP. Gut hyperpermeability is commonly present, despite the absence of splanchnic ischemia.

Decisions to be made when initiating enteral nutrition

Enteral nutrition support is preferred to parenteral or no nutritional support, but many patients who could benefit receive inadequate enteral feeding. Many decisions must be made before initiating enteral nutrition support; including if and when enteral nutrition should be started, which formula should be used, and how enteral nutrition support should be monitored. The gastroenterologist should be able to understand and evaluate these decisions in all patients potentially requiring nutritional support.

Altered intestinal function in patients with chronic heart failure

OBJECTIVES

We evaluated morphology and function of the gut in patients with chronic heart failure (CHF).

BACKGROUND

Intestinal translocation of bacterial endotoxin may contribute to the inflammatory state observed in patients with CHF. The morphology and function of the gut may be abnormal.

METHODS

We studied 22 patients with CHF (age 67 +/- 2 years, left ventricular ejection fraction [LVEF] 31 +/- 1%, New York Heart Association functional class 2.3 +/- 0.1, peak VO2 15.0 +/- 1.0 ml/kg/min) and 22 control subjects (62 +/- 1 years, LVEF 68 +/- 2%, peak VO2 24.7 +/- 1.3 ml/kg/min). Bowel wall thickness was assessed by transcutaneous sonography, small intestinal permeability by the lactulose-mannitol test, passive carrier-mediated transport by D-xylose test, large intestinal permeability by sucralose test (5- and 26-h urine collection, high-performance liquid chromatography), and mucosal bacterial biofilm by fluorescence in situ hybridization in biopsies taken during sigmoidoscopy.

RESULTS

Chronic heart failure patients, compared with control patients, showed increased bowel wall thickness in the terminal ileum (1.48 +/- 0.16 mm vs. 1.04 +/- 0.08 mm), ascending colon (2.32 +/- 0.18 mm vs. 1.31 +/- 0.14 mm), transverse colon (2.19 +/- 0.20 vs. 1.27 +/- 0.08 mm), descending colon (2.59 +/- 0.18 mm vs. 1.43 +/- 0.13 mm), and sigmoid (2.97 +/- 0.27 mm vs. 1.64 +/- 0.14 mm) (all p < 0.01). Chronic heart failure patients had a 35% increase of small intestinal permeability (lactulose/mannitol ratio: 0.023 +/- 0.001 vs. 0.017 +/- 0.001, p = 0.006), a 210% increase of large intestinal permeability (sucralose excretion: 0.62 +/- 0.17% vs. 0.20 +/- 0.06%, p = 0.03), and a 29% decrease of D-xylose absorption, indicating bowel ischemia (26.7 +/- 3.0% vs. 37.4 +/- 1.4%, p = 0.003). Higher concentrations of adherent bacteria were found within mucus of CHF patients compared with control subjects (p = 0.007).

CONCLUSIONS

Chronic heart failure is a multisystem disorder in which intestinal morphology, permeability, and absorption are modified. Increased intestinal permeability and an augmented bacterial biofilm may contribute to the origin of both chronic inflammation and malnutrition.

Probiotic bacteria prevent hepatic damage and maintain colonic barrier function in a mouse model of sepsis

A breakdown in intestinal barrier function and increased bacterial translocation are key events in the pathogenesis of sepsis and liver disease. Altering gut microflora with noninvasive and immunomodulatory probiotic organisms has been proposed as an adjunctive therapy to reduce the level of bacterial translocation and prevent the onset of sepsis. The purpose of this study was to determine the efficacy of a probiotic compound in attenuating hepatic and intestinal injury in a mouse model of sepsis. Wild-type and interleukin-10 (IL-10) gene-deficient 129 Sv/Ev mice were fed the probiotic compound VSL#3 for 7 days. To induce sepsis, the mice were injected with lipopolysaccharide (LPS) and D-galactosamine (GalN) in the presence and absence of the peroxisome proliferator-activated receptor gamma (PPARgamma) inhibitor GW9662. The mice were killed after 6 hours, and their colons were removed for the measurement of the cytokine production and epithelial function. The functional permeability was assessed by the mannitol movement and cyclic adenosine monophosphate-dependent chloride secretion in tissue mounted in Ussing chambers. The livers were analyzed for bacterial translocation, cytokine production, histological injury, and PPARgamma levels. The tissue levels of tumor necrosis factor alpha, interferon gamma, IL-6, and IL-12p35 ribonucleic acid were measured by semiquantitative reverse transcription polymerase chain reaction. Mice injected with LPS/GalN demonstrated a breakdown in colonic barrier function, which correlated with enhanced proinflammatory cytokine secretion, bacterial translocation, and significant hepatic injury. A pretreatment with oral probiotics prevented the breakdown in intestinal barrier function, reduced bacterial translocation, and significantly attenuated liver injury. The inhibition of PPARgamma with GW9662 abrogated the protection induced by probiotics.

CONCLUSION

Orally administered probiotics prevented liver and intestinal damage in a mouse model of sepsis through a PPARgamma-dependent mechanism.

Lactate and glycerol released to the intestinal lumen reflect mucosal injury and permeability changes caused by strangulation obstruction

BACKGROUND

The present study evaluates whether microdialysis of glycerol and lactate reflects mucosal injury and permeability changes after strangulation obstruction of the pig small intestine.

METHODS

Strangulation obstruction was induced by tightening a rubber band around a small bowel loop until its venous pressure increased to a level just below diastolic aortic pressure (partial strangulation), or further until cessation of flow in the main feeding artery (total strangulation). Mucosal injury and permeability of marker molecules from blood to lumen and vice versa was compared to release of glycerol and lactate to the intestinal lumen.

RESULTS

Mucosal injury, hyperpermeability, and release of glycerol were more pronounced after total than after partial strangulation. In animals with partial strangulation there was a complete restitution of the surface epithelium, and luminal glycerol and lumen-to-blood permeability of polyethylene glycol 4000 remained low. Such animals showed a sustained elevation of lactate and blood-to-lumen permeability of fluorescein isothiocyanate dextran after 2 h of partial strangulation, but a decline to baseline levels of these parameters in animals with 1 h partial strangulation.

CONCLUSION

Microdialysis of lactate and glycerol in the intestinal lumen may be used to assess structural and functional changes of the intestinal mucosa after strangulation obstruction.

Mechanical ventilation strategies in the management of congenital diaphragmatic hernia

Most infants with congenital diaphragmatic hernia (CDH) require respiratory support. The goal of this report is to present an overview of mechanical ventilation strategies in the management of infants with CDH. The anatomic and physiologic limitations in the lungs of infants with diaphragmatic hernia make decisions on the best strategy and use of mechanical ventilation challenging. We will briefly review lung development in infants with CDH, identifying factors that provide a basis for lung protection strategies. Background on the use of specific mechanical ventilation modes and the rationale for each are provided. Finally, we review mechanical ventilation practices described in published case series of successful CDH management, with a brief review of additional treatments, including inhaled nitric oxide and extracorporeal membrane oxygenation. Although details of a single specific best strategy for mechanical ventilation for CDH infants cannot be identified from current literature, a lung protection ventilation approach, regardless of the device used, appears to reduce mortality risk.

Effects of probiotic therapy in critically ill patients: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Multiple organ dysfunction syndrome (MODS) is a major cause of mortality in intensive care units. A breakdown in gut barrier function and immune dysfunction are associated with the onset of MODS. Probiotic bacteria have been shown to modulate intestinal barrier and immune function.

OBJECTIVE

This study assessed the efficacy of a probiotic compound in a viable and nonviable formulation in modulating intestinal permeability and immune function and preventing the onset of MODS in patients in the intensive care unit.

DESIGN

A double-blind, randomized controlled trial was conducted in the intensive care unit of a tertiary care teaching hospital. Twenty-eight critically ill patients admitted to the intensive care unit were randomly assigned to receive 1 of 3 treatments daily for 7 d: 1) placebo, 2) viable probiotics, or 3) equivalent probiotic sonicates. MODS scores and systemic concentrations of immunoglobulin (Ig) A and IgG were measured on days -1, 4, and 7, and intestinal permeability measurements were taken daily.

RESULTS

The patients responded to viable probiotics with a significantly larger increase in systemic IgA and IgG concentrations than in the patients who received placebo or sonicates (P < 0.05). MODS scores were not significantly affected by probiotic treatment. Over the study period, intestinal permeability decreased in most patients.

CONCLUSION

Patients receiving viable probiotics show a greater enhancement in immune activity than do patients receiving either placebo or probiotic bacterial sonicates.

Tight junction proteins in gallbladder epithelium: different expression in acute acalculous and calculous cholecystitis

There is a paucity of information of tight junction (TJ) proteins in gallbladder epithelium, and disturbances in the structure of these proteins may play a role in the pathogenesis of acute acalculous cholecystitis (AAC) and acute calculous cholecystitis (ACC). Using immunohistochemistry, we investigated the expression of TJ proteins claudin-1, -2, -3, and -4, occludin, zonula occludens (ZO-1), and E-cadherin in 9 normal gallbladders, 30 gallbladders with AAC, and 21 gallbladders with ACC. The number of positive epithelial and endothelial cells and the intensity of the immunoreaction were determined. Membrane-bound and cytoplasmic immunoreactivities were separately assessed. We found that TJ proteins were uniformly expressed in normal gallbladder epithelium, with the exception of claudin-2, which was present in less than half of the cells. In AAC, expression of cytoplasmic occludin and claudin-1 were decreased, as compared with normal gallbladder. In ACC, expression of claudin-2 was increased, and expression of claudin-1, -3, and -4, occludin, and ZO-1 were decreased, as compared with normal gallbladder or AAC. We conclude that there are significant differences in expression of TJ proteins in AAC and ACC, supporting the idea that AAC represents a manifestation of systemic inflammatory disease, whereas ACC is a local inflammatory and often infectious disease.

Recovery of mucosal barrier function in ischemic porcine ileum and colon is stimulated by a novel agonist of the ClC-2 chloride channel, lubiprostone

Previous studies utilizing an ex vivo porcine model of intestinal ischemic injury demonstrated that prostaglandin (PG)E(2) stimulates repair of mucosal barrier function via a mechanism involving Cl(-) secretion and reductions in paracellular permeability. Further experiments revealed that the signaling mechanism for PGE(2)-induced mucosal recovery was mediated via type-2 Cl(-) channels (ClC-2). Therefore, the objective of the present study was to directly investigate the role of ClC-2 in mucosal repair by evaluating mucosal recovery in ischemia-injured intestinal mucosa treated with the selective ClC-2 agonist lubiprostone. Ischemia-injured porcine ileal mucosa was mounted in Ussing chambers, and short-circuit current (I(sc)) and transepithelial electrical resistance (TER) were measured in response to lubiprostone. Application of 0.01-1 microM lubiprostone to ischemia-injured mucosa induced concentration-dependent increases in TER, with 1 microM lubiprostone stimulating a twofold increase in TER (DeltaTER = 26 Omega.cm(2); P < 0.01). However, lubiprostone (1 microM) stimulated higher elevations in TER despite lower I(sc) responses compared with the nonselective secretory agonist PGE(2) (1 microM). Furthermore, lubiprostone significantly (P < 0.05) reduced mucosal-to-serosal fluxes of (3)H-labeled mannitol to levels comparable to those of normal control tissues and restored occludin localization to tight junctions. Activation of ClC-2 with the selective agonist lubiprostone stimulated elevations in TER and reductions in mannitol flux in ischemia-injured intestine associated with structural changes in tight junctions. Prostones such as lubiprostone may provide a selective and novel pharmacological mechanism of accelerating recovery of acutely injured intestine compared with the nonselective action of prostaglandins such as PGE(2).

Clinical study on therapy of clearing hallow viscera in treating critical patients with gastro-enteric function disorder

OBJECTIVE

To explore the clinical effect of therapy of clearing hallow viscera in treating critical patients with gastro-enteric function disorder (GEFD).

METHODS

Retrospective analysis was carried out on 96 critical patients. They were 48 patients in the treated group treated with Dachengqi Decoction and 48 patients in the control group treated with Western medicine for promoting gastric dynamic force. The recovery rate, recovery time of gastro-enteric function, incidence rate and fatality rate of multiple organ dysfunction syndrome (MODS), as well as the level of plasma endotoxin (ET) before and after treatment between the two groups were compared.

RESULTS

Comparison between the two groups in gastro-enteric function recovery rate (81.3% vs 45.8%), functional disorder sustaining time in patients who got recovered (1.2 +/- 0.3 days vs 4.0 +/- 1.1 days), incidence rate (29.17% vs 52.08%) and fatality rate (28.57% vs 56.00%) of MODS all showed significant difference (P < 0.05 or P < 0.01). The plasma level of ET after treatment in the treated group was significantly lower than that in the control group (P < 0.05).

CONCLUSION

Therapy of clearing hallow viscera has a good effect in treating critical patients with gastro-enteric function disorder, and could reduce the incidence and fatality of MODS.

Negative mesenteric effects of lung recruitment maneuvers in oleic acid lung injury are transient and short lasting

OBJECTIVE

To test the hypothesis that repeated recruitment maneuvers (RMs) have sustained negative effects on mesenteric circulation, metabolism, and oxygenation 60 mins after RMs in pigs with oleic acid lung injury. Further, we aimed to test the hypothesis that an infusion of prostacyclin (PC) at 33 ng.kg.min would attenuate such possible negative mesenteric effects.

DESIGN

Randomized, experimental, controlled study.

SETTING

University hospital animal laboratory.

SUBJECTS

A total of 31 anesthetized, fluid-resuscitated pigs with oleic acid lung injury.

INTERVENTIONS

: Animals were randomized to one of the following four groups: a control group (n = 7) that received no intervention, recruitment group (n = 8) that underwent the RM sequence, a prostacyclin group (n = 8) that received an infusion of PC, and a recruitment-prostacyclin group (n = 8) that received an infusion of PC and concomitant RM sequence.

MEASUREMENTS AND MAIN RESULTS

We measured systemic and mesenteric hemodynamic variables, jejunal mucosal perfusion, mesenteric lactate flux, jejunal tissue oxygen tension, and mesenteric oxygen delivery, uptake, and extraction ratio. Five minutes after RMs, mesenteric oxygen extraction ratio and mesenteric lactate flux were more prominently increased in the recruitment group, giving evidence of worsened mesenteric conditions after RMs. These signs of worsened conditions were further supported by more decreased jejunal tissue oxygen tension and portal vein oxygen saturation in the recruitment group. PC preserved mesenteric oxygenation, as indicated by less of a decrease in portal vein oxygen saturation at the time corresponding to 5 mins after RM and less of a decrease in mesenteric oxygen delivery at the time corresponding to 15 mins after RM. PC preserved mesenteric oxygenation as indicated by less of a decrease in portal vein oxygen saturation at 5 mins after RM and an attenuated increase in mesenteric oxygen extraction ratio at 5 mins after RM. There was a trend toward worsened jejunal mucosal perfusion, although not significant.

CONCLUSIONS

In an oleic acid lung injury model, three repeated RMs did not improve systemic oxygenation or lung mechanics. Negative effects on mesenteric oxygenation and metabolism were transient and short lasting. The intestinal effects of PC during RMs were minor and opposing, showing preserved oxygenation but a trend toward worsened mucosal perfusion.

The effect of glutamine-enriched enteral nutrition on intestinal permeability in very-low-birth-weight infants: a randomized controlled trial

BACKGROUND

Very-low-birth-weight (VLBW) infants are susceptible to glutamine depletion. Glutamine depletion has negative effects on intestinal integrity. The lower infection rate in VLBW infants receiving glutamine-enriched enteral nutrition may originate from improved intestinal integrity, as reflected by decreased intestinal permeability. The aim of our study was to investigate whether glutamine-enriched enteral nutrition in VLBW infants enhances the normal decrease in intestinal permeability, as measured by the sugar absorption test (SAT).

METHODS

In a double-blind, randomized, placebo-controlled trial, VLBW infants (gestational age <32 weeks or birth weight <1,500 g) received enteral glutamine supplementation (0.3 g/kg/d) or an isonitrogenous placebo supplementation (alanine) between days 3 and 30 of life. Intestinal permeability, determined from the urinary lactulose/mannitol (L/M) ratio after an oral dose of lactulose and mannitol, was assessed at 4 time points: before the start of the study, and at days 7, 14, and 30 of life.

RESULTS

At least 2 SATs were performed in 45/52 (86%) and 45/50 (90%) infants in the glutamine-supplemented and control groups, respectively. Baseline patient and nutrition characteristics were not different between the groups. There was no effect of glutamine-enriched enteral nutrition on the decrease of the L/M ratio between the start and end of the study (p = .78). In both treatment groups, median urinary lactulose concentrations decreased (p < .001), whereas median urinary mannitol concentrations increased (p = .003).

CONCLUSIONS

Glutamine-enriched enteral nutrition does not enhance the postnatal decrease in intestinal permeability in VLBW infants. Any beneficial effect of glutamine may involve other aspects of intestinal integrity; for example, modulation of the intestinal inflammatory response.

Anti-HMGB1 neutralizing antibody ameliorates gut barrier dysfunction and improves survival after hemorrhagic shock

Intestinal barrier dysfunction occurs following hemorrhagic shock and resuscitation (HS/R). High-mobility group B1 (HMGB1) has been shown to increase the permeability of Caco-2 human enterocyte-like epithelial monolayers in vitro. In this study, we found that serum concentrations of HMGB1 were higher in blood samples obtained from 25 trauma victims with hemorrhagic shock than in 9 normal volunteers. We also studied whether treatment with anti-HMGB1 antibody can ameliorate HS/R-induced gut barrier dysfunction in mice. Animals were shocked by withdrawal of blood to maintain mean arterial pressure at 25 to 30 mmHg for 2 h. After resuscitation with shed blood plus Ringer's lactate solution, the mice were treated with either anti-HMGB1 antibody or nonimmune rabbit IgG. Serum HMGB1 concentrations were significantly higher in trauma victims than control mice. Treatment with anti-HMGB1 antibody improved survival at 24 h and ameliorated the development of ileal mucosal hyperpermeability to FITC-labeled dextran. At 24 h after HS/R, treatment with anti-HMGB1 antibody decreased bacterial translocation to mesenteric lymph nodes and was associated with lower circulating concentrations of IL-6 and IL-10. These data support the notion that HMGB1 is a mediator of HS/R-induced gut barrier dysfunction and suggest that anti-HMGB1 antibodies warrant further evaluation as a therapeutic to ameliorate the morbidity of HS/R in trauma patients.

Critical care nutrition: getting involved as a gastrointestinal endoscopist

The route, timing, and volume of enteral feeding delivered to a patient in the intensive care unit have a profound effect on clinical outcome. At the height of critical illness, problems with ileus, aspiration, and the systemic inflammatory response syndrome make the provision of enteral nutrients a difficult and somewhat risky endeavor. The gastrointestinal endoscopist has the technical skills to place feeding tubes deep within the jejunum and an underlying expertise in gut physiology to monitor patients effectively once feeds are initiated. Attention to detail in the techniques for attaining enteral access, early identification of potential problems, and quick institution of simple endoscopic strategies help improve delivery of nutrition support, minimize the likelihood for in-hospital complications, and optimize patient outcome.

Increased colorectal permeability in patients with severe sepsis and septic shock

OBJECTIVE

To develop a method for the assessment of colorectal permeability in septic patients.

DESIGN AND SETTING

Observational study in ICUs at two university hospitals.

PARTICIPANTS

Nine patients with septic shock and abdominal focus of infection, 7 with severe sepsis and pulmonary focus and 8 healthy subjects.

MEASUREMENTS AND RESULTS

Colorectal permeability was assessed as the initial appearance rate of (99m)Tc-DTPA in plasma after instillation into the rectal lumen and as the cumulative systemic recovery at 1h. To calculate the latter, volume of distribution and renal clearance of (99m)Tc-DTPA was estimated by an i.v. bolus of (51)Cr-EDTA. The initial rate of permeability was increased in patients with septic shock and severe sepsis compared with controls [29.0 (3.7-83.3), 20.6 (3.6-65.5) and 6.0 (2.2-9.6)cpm ml(-1)min(-1), respectively, p<0.05)] with a positive linear trend (r (2)=0.27, p=0.01) and correlated to L-lactate concentrations in the rectal lumen (r (2)=0.39, p<0.05). The cumulative permeability was also increased in patients with septic shock and severe sepsis compared with controls [2.07 (0.05-15.7), 0.32 (0.01-1.2) and 0.03 (0.01-0.06) per thousand, respectively, p<0.01] and correlated to the initial permeability rate (r (2)=0.26, p=0.01).

CONCLUSIONS

In septic patients, the systemic recovery of a luminally applied marker of paracellular permeability was increased and related to the luminal concentrations of L-lactate and possibly to disease severity. This suggests that the assessment of colorectal permeability by systemic recovery of (99m)Tc-DTPA is valid and that metabolic dysfunction of the mucosa contributes to increased permeability of the large bowel in patients with severe sepsis and septic shock.